You mentioned pulling the rounds left and found proper powder charges so I'll assume the measure is working. The bullet rotating after seating caught my attention also. Case tension alone, as scooter123 said, should have you looking for pliers to turn a bullet. No case tension, no pressure. Either your bullet is undersized or your belling plug is way to deep.
The first time I switched from 44 special to 44 magnum I forgot all about the belling plug going deeper into the case. The first case I belled I knew what I did. A .430 bullet almost disappeared into the case!